Trapped moisture is usually not desirable, and your home is no exception. Without proper roof ventilation, the attic and roof become vulnerable to mold and mildew, warped materials, and premature deterioration.
A roof vent is designed to allow hot air and moisture to escape the attic. There several choices in roof ventilation that accomplish this task in different ways. Each type has its pros and cons.
A static vent has no moving parts. It simply creates an opening for hot air and moisture to escape, but only allows ventilation in the immediate area where it is installed. There are several types of static vents, such as box vents, off-ridge vents, and cupola vents. Using natural convection, they create an opening for the rising hot air and moisture to escape. Static vents are most effective when installed as close to the roof ridge as possible. However, due to their limited effectiveness, numerous static vents are often required. If not enough vents are installed, this can cause an uneven distribution of hot and cold zones, meaning that sections of the roof could age faster than others.
Power vents, also known as PAVs (Power Attic Vents) use electricity to pull air out of the attic. Though they are effective, they also add an ongoing expense to a homeowner’s utility bill. Most are hardwired into the home’s electrical system, but there are models with built-in solar panels to power the unit. Some power vents are controlled by an adjustable thermostat which triggers the fan to kick on when the attic reaches a certain temperature. They are also available with a humidistat that will turn on when a certain level of humidity is reached. One downside to this type of roof ventilation is that many homeowners don’t notice when their power vent is no longer functioning or needs maintenance. For this reason, a regular inspection is recommended.
Turbine vents (seen in the photo at the top of this page), also called whirlybirds, are not static vents, as they have moving parts. However, they also do not have motors and instead rely on wind to power their movement. This spinning action, triggered by wind, draws hot air and moisture out of the attic. When the wind is not blowing, or if they are used in an area that does not get a lot of wind, they lack effectiveness. Like anything, turbine vents are available in differing degrees of quality. Cheaper versions are often noisy or make a squeaking sound as they spin in the wind.
A ridge vent is another type of static vent, but it typically offers the most roof ventilation for the money and is ideal for most homes. It is positioned along the entire peak of the roof and allows excellent exhaust of heat and moisture year-round. In fact, used in conjunction with undereave venting, ridge vents are often considered the most effective and efficient attic ventilation system. While other types of vents, particularly other static vents, only allow ventilation of the area directly adjacent to them, ridge vents provide even temperature distribution.
Which Roof Ventilation System is Best?
There is no “one” best type of roof ventilation system. The best ventilation system for your home will take into account the size of the structure, airflow, and roof design. Not all homes are designed the same way and are not all exposed to the same climate. Therefore, not every home is best served by the same roof ventilation options. To answer the questions about which roof ventilation system is best for your home, find an unbiased roofing contractor who will design a custom ventilation system for your home.
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